No. I think it is a repetitive rate. Thus, for example it may sample 1000 samples per sweep, but each sample is delayed by 10ps from the previous sweep. Thus over a series of sweeps you get the equivalent of a 100GHz sample rate. But the aperture (sample) period must still be very short (likely less than 10ps) to get a clean sample and that's obviously not a trivial requirement.
But that's usually not a serious limitation since it's not often that you have only a single 100ps pulse that you need to see.